Read the following text to answer the question!

    One Sunday morning last week, Mary went out on a picnic with some other girls. It was a fine day. The sky was clear. The sun was shining. They did not think it was going to rain, so they did not bring any raincoat.

    Suddenly the wind began to blow. There were dark clouds in the sky. The rain came down. It rained heavily. There were lightning and thunder. Mary and all the other girls were very wet. They were very cold.

    The next morning Mary did not go to school. She was absent. Miss Rosy was surprised. She asked the pupils in the class where Mary was. John stood up and said to the teacher. He said that Mary had got a cold and a cough. Miss Rosy was very sorry for her.

What is the purpose of the story above?